Praise be to Allah.
The Muslim is obliged to submit to the ruling of Allah, may He be exalted, even if he does not understand the wisdom behind it, because Allah has perfect wisdom, and He has not prescribed anything except for a reason. Allah, may He be exalted, says (interpretation of the meaning):
“But no, by your Lord, they can have no Faith, until they make you (O Muhammad SAW) judge in all disputes between them, and find in themselves no resistance against your decisions, and accept (them) with full submission”
Part of the wisdom of sharee‘ah that it does not differentiate between things that are similar and it does not regard as equal things that are different. If Islam differentiates between two things, such as the duff and the tablah (another kind of drum), then they are definitely not the same and there is a difference between them which dictates that they should come under different rulings.
But… There are some people whom Allah has enabled to understand this difference and others who do not understand it, but in either case it is obligatory to submit to the ruling of Allah, may He be exalted.
The difference between the duff and the tablah is that the sound of the duff is less stirring and it has less of an effect on the soul than the tablah. The hollow space inside of the tablah causes vibration and a more stirring sound, which does not happen with the duff, because it has no hollow space inside, and its sound is also less powerful than that of the tablah.
For this reason sharee‘ah forbids the kind of duff that has jangling pieces of metal around it (i.e., tambourine), because the jangling pieces make more of a stirring sound than the duff that does not have them.
The daff is the least stirring of all musical instruments, hence sharee‘ah has permitted it in some cases, because of the interests served by that, such as announcing a wedding and making it well known among the people.
For more information please see the answer to question no. 20406.
And Allah knows best.